Metal roof structures typically comprise a series of parallel rafter beams extending across the building in one direction and purlin beams parallel to each other mounted on top of the rafters extending in a direction normal to the rafters. Insulation material in long sheets is placed in the area between purlins. The sheets of insulation material can be laid along the length of the purlins or across the purlins in a direction normal to the purlins. Hard roofing material such as metal decking is then attached on top of the purlins over the insulation material. Because the hard roofing material comes in long sheets and the roofs generally have two sloped sections, it is customary to construct the roof along the length of the structure from one end to the other. The workers stand on the previously laid section of roof to construct the next section.
The insulation material must be supported between the purlins beneath the hard roofing material. Various methods of supporting the insulation material have been used. Some systems use a support sheet (also referred to as a facing or vapor barrier) to support the insulation material. The support sheet is draped from the adjacent purlins and the insulation material is placed on top of the support sheet. A carriage has been used to aid in the dispensing of the support sheet. The carriage is positioned on top of the purlins and travels the length of the purlins during the roof construction. A roll of the support sheet material is mounted on the carriage and the support sheet is payed out from the roll and placed on top of the purlins. As the carriage travels the length of the purlins, the support sheet is draped across the purlins.
Insulation material which is laid along the length of the purlins on top of the support sheet is typically dispensed from a roll (although other types of insulation material may be utilized). The roll of insulation may be provided on a carriage, similar to the support sheet, to be payed out as the carriage travels along the purlins. A support sheet and insulation may be simultaneously payed out from a single carriage.